NEW YORK (Reuters) - Viacom Inc's MTV Networks is expected to on Tuesday announce plans to merge its online digital music offerings into a joint venture with music software company RealNetworks Inc, the Wall Street Journal reported.

The newspaper's online edition, citing people familiar with the matter, said MTV and RealNetworks, which runs subscription digital-music service Rhapsody, are joining forces in a bid to create stiffer competition for Apple Inc's iTunes online music store.

Neither Viacom or RealNetworks could immediately be reached for comment.

Verizon Wireless, a venture of Verizon Communications Inc and Vodafone Group Plc, is expected to supply mobile distribution for the joint venture's digital content, the newspaper said, citing one of its sources.

The pact with Verizon Wireless could bolster the new venture's battle against iTunes, the Journal said, after Apple drew widespread criticism from mobile operators and consumers when it made AT&T Inc the sole U.S. provider of its iPhone.

The pact with RealNetworks likely means the end of MTV's Urge, a digital service launched last year with Microsoft Corp, the Journal reported.